Application of the Law of Chemical Equilibrium (law of Mass Action) to Biological Problems

The concept of balanced chemical reactions, introduced by Wenzel in 1777l and made more exact by Berthollet in 1801, was put into the quantitatively useful form of the law of mass action by Guldberg and Waage in 1867. In 1877 van’t Hoff showed how this law could be derived from the principles of thermodynamics, without introducing the vague idea of chemical force, and in 1887 Arrhenius applied the same law to the dissociation of electrolytes in solution. The earliest applications of the law of chemical equilibrium, which was originally derived from the law of mass action, to physiological problems were that of Hiifner (1890) to the dissociation of oxyhemoglobin, and that of L. J. Henderson (1908), characterized by Peters and Van Slyke (1931) as “the first unified explanation of the physiological and physicochemical mechanisms by which the body maintains its normal acid-base balance.” This review will attempt to set forth the concepts essential to a working knowledge of the law of chemical equilibrium, and to illustrate the adapt ability of this law to specific problems, rather than to assemble the many important though unrelated contributions which have made use of it. The equally important applications of the law of mass action to the kinetics of chemical reactions will be considered only in so far as they have been applied to physiological problems studied also by the law of chemical equilibrium.